Vitreous fluorophotometry will be used to quantitatively evaluate the blood-ocular barriers in juvenile- and adult-onset diabetes mellitus. A long-term study of juvenile-onset, insulin-dependent diabetics will be done with attempts to correlate serial vitreous fluorophotometry measurements with serial hemoglobin-Alc measurements. Vitreous fluorophotometry measurements will also be correlated with the presence or absence of retinopathy in adult-onset diabetics and used to compare the various treatment modalities for this disease.